# Angular Velocity and Acceleration

Definition: Angular Velocity

Angular velocity of a rigid body is the rate of change of its angular position. Thus, if = at t = t1 , and = at t = t2 , then the average angular velocity of the body over the time interval t = t2 - t1 is: = = . (4)

As for linear motion, the instantaneous velocity is obtained by making the time interval very small: = . (5)

The units of angular velocity are most conveniently given in rads/sec, but can also be expressed in revolutions/sec or degrees/sec using the conversions given above.

Definition: Angular Acceleration

Angular Acceleration is the rate of change of angular velocity with time. The average angular acceleration of a rigid body over a time interval t = t2 - t1 is: = = . (6)

The instantaneous angular acceleration is obtained by taking a very small time interval: =  . (7)

The units of angular acceleration are normally radians/sec 2.    Next: Formulae for Constant Angular Up: Circular Motion and the Previous: Introduction